Looking at the new iOS and macOS features, they seem to be quite “destructive” on a feature level. (F.e. The new reminders app)
Does that mean you would need to have your entire device list on the same version at least?
Or will the new features “play nice” with older OS’s once the public betas roll around.
Does anyone know?
I do not know, but I have been asking myself the same question.
I really want to install iPadOS on my iPad, but I am not so sure about putting Catalina on my Mac…
These screenshots were taken when I installed the beta on my iPad Pro:
I chose to upgrade later, and I’ll do that when the public beta is available 
One can’t have enough MacBooks 
Good to see there is an “upgrade later”. I, too, was worried about this since I’ve got systems that won’t or can’t be upgraded to Catalina but iOS devices that will be upgraded.
This looks the same as when Notes was upgraded. When I upgraded on one device, it just locked me out on the unsupported devices until they upgraded, so there was no risk of data loss (if I remember correctly).
